765

class Solution {
int ans = 0;
vector<int> p;
public:
    int find(int x){
        return (x == p[x]) ? x : (p[x] = find(p[x]));
    }

    void unionSet(int x, int y){
        int px = find(x);
        int py = find(y);
        if(px != py){
            p[py] = px;
            ans++;
        }
    }

    int minSwapsCouples(vector<int>& row) {
        p.resize(row.size());
        for(int i=0; i<row.size(); i+=2){
            p[row[i]] = row[i];
            p[row[i+1]] = row[i];
        }
        for(int i=0; i<row.size(); i+=2)
            unionSet(i,i+1);
        return ans;
    }
};